What makes best ground?


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Old 12-22-03, 01:20 PM
zeringue
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What makes best ground?

Is 8' depth of copper ground rod good enough, or should two 8' be connected and driven to 16'? I'm doing some re-wiring and just wondering if what's here is good enough for residential dwelling. If there are any "standards" specs on this, please let me know where to look. Thanks!
 
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Old 12-22-03, 04:19 PM
J
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Two 8' rods 10' apart is normal. You don't connect them together into a 16' rod.
 
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Old 12-22-03, 05:01 PM
R
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You need a second ground as well. This can be the water pipe, if it is metal and if it extends outside the house and into the ground for at least ten feet. Whether the water pipe is used as a ground or not, the interior water pipes must be connected to your ground system if they are metal.
 
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Old 12-22-03, 05:34 PM
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NEC 250.50 through 250.70 is all about grounding electrodes and conductors. If you wish to look it up.

Basically if you have a metal water pipe feeding your house, and it extends at least 10' from the house, it must be used as an electrode. You must also jump out the meter and any other equipment that breaks or can break the pipe integrity, ie: unions.
If you use the water pipe as an electrode you MUST supplement that with a rod electrode.

If no metal water pipe is present only ONE (or more) electrode(rod) is required by the NEC. Local codes vary greatly as do the grounding electrode conductor sizing. The catch is the rod must have a resistance of 25 ohms or less. If not it must be supplemented by another electrode, at least 6' apart. I will say, in all my years I have never seen an inspector ohm out a ground rod. It's more of a judgement call by the installer.

As racraft said. In any case the metal piping in the house must be bonded.
 
 

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